There are three possible cases I can see:
A) The person legitimately did not do anything bad and is being unfairly punished, in which case the inability to speak is nothing but a detriment to the rest of his team's ability to play the game.
B) The person does indeed deserve a punishment for being an unpleasant, foul mouthed individual. In which case why would we want to play with him at all? LPQ exists for a reason. Now instead others are stuck playing with an angry ass, only it's a mute angry ass, when previously he'd have been sent down to LPQ.
C) He's a fringe case and normally wouldn't rage/insult enough to warrant anything, but it went wrong this once. If he's a pleasant enough player normally, see A).
In no case whatsoever is having a teammate unable to communicate at all a positive change from the previous report system. If you find that someone is being an asshole, the mute button takes less than 2 seconds to hit, and you could use a report to send him to LPQ instead of letting him continue to queue.